title: The photoconvertible water-soluble chlorophyll-binding protein of Chenopodium album is a member of DUF538, a superfamily that distributes in Embryophyta.
abstract: Various plants possess hydrophilic chlorophyll (Chl) proteins known as water-soluble Chl-binding proteins (WSCPs). WSCPs exist in two forms: Class I and Class II, of which Class I alone exhibits unique photoconvertibility. Although numerous genes encoding Class II WSCPs have been identified and the molecular properties of their recombinant proteins have been well characterized, no Class I WSCP gene has been identified to date. In this study, we cloned the cDNA and a gene encoding the Class I WSCP of Chenopodium album (CaWSCP). Sequence analyses revealed that CaWSCP comprises a single exon corresponding to 585bp of an open reading frame encoding 195 amino acid residues. The CaWSCP protein sequence possesses a signature of DUF538, a protein superfamily of unknown function found almost exclusively in Embryophyta. The recombinant CaWSCP was expressed in Escherichia coli as a hexa-histidine fusion protein (CaWSCP-His) that removes Chls from the thylakoid. Under visible light illumination, the reconstituted CaWSCP-His was successfully photoconverted into a different pigment with an absorption spectrum identical to that of native CaWSCP. Interestingly, while CaWSCP-His could bind both Chl a and Chl b, photoconversion occurred only in CaWSCP-His reconstituted with Chl a.
authors.affiliation: Department of Biomolecular Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan.
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Takahashi
authors.forename: Mami
authors.initials: M
authors.lastname: Yoshikawa
authors.forename: Akiko
authors.initials: A
authors.lastname: Kamada
authors.forename: Takayuki
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Akira
authors.initials: A
authors.lastname: Uchida
authors.forename: Katsumi
authors.initials: K
authors.lastname: Nakayama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Satoh
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D027463:Chenopodium album / Q000378:metabolism*; D061146:Chlorophyll Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D020539:Sequence Analysis, Protein
chemical_list: D061146:Chlorophyll Binding Proteins
keywords: C-terminal; Chenopodium album; Chl; Chlorophyll; DUF; DUF538; IPTG; N-terminal; Photoconversion; WSCP; Water-soluble chlorophyll-binding protein; amino terminal; carboxy terminal; chlorophyll; domain of unknown function; isopropyl β-d-1-thiogalactopyranoside; water-soluble chlorophyll-binding protein